The present invention relates generally to the field of gimbal type devices and to the field of devices for providing two orthogonal degrees of freedom to a load device. More particularly, the present invention is related to the field of servo controlled, rate stabilizing platforms for sensor systems which are used for guidance systems such as missile guidance systems and surveillance systems for data/intelligence gathering and target tracking.
Traditionally, stabilized sensor platforms have been very high cost systems due to the fact that they are intricate and complex mechanical structures. Packaging of the sensor system on the stabilized platform is an involved process. Volume and weight restrictions are very costly packaging requirements to meet. Stabilized missile sensors require at least two degrees of freedom of movement (azimuth and elevation). These two degrees of freedom of movement have been accomplished in the past by an inner/outer gimbal arrangement of the stabilized platform.
To maintain tracking accuracies and pointing error tolerances, the inner and outer gimbals of the platform must be precisely located and their movement must be within a given tolerance. Many schemes in the past have been used to configure the inner and outer gimbals to maintain these precision movements. They have all, however, been very high cost configurations and have restricted the weight and volume limitation of the sensor which ultimately is mounted to the platform. The most common scheme on the outer gimbal alignment has been to cut bearing races into the edge of the gimbal itself with recirculating bearings imbedded into the bearing race. Thus the whole outer gimbal in this prior art design is a complex bearing system in itself. The material used to make the outer gimbal in this design has to be of hardened steel to facilitate the bearing races.
Traditionally, moreover, the inner gimbal torque power unit has been mounted on the inner gimbal itself. This has restricted the size of the torque power unit (such as a servomotor) which limited the available torque to drive the inner gimbal. By mounting the torque unit on the inner gimbal, the sensor packaging was restricted because the torquer or torque power unit took up much of the packaging volume around the inner axis of rotation. Proper sensor operation requires the sensor to be located at the axis of rotation.